Mysimba experiences split into two camps. One group reports that the urge to eat drops noticeably, the other stops within weeks because of nausea or insomnia. Both pictures are accurate, and the research shows why.
Mysimba contains two substances: naltrexone and bupropion. Neither was originally a weight-loss drug.
What appears on no experience page is that bupropion can slightly raise your blood pressure and heart rate. That makes this the one weight-loss drug whose most important check is not a blood value but a blood pressure monitor.
What do Mysimba users report?
The most cited positive effect is less appetite and fewer thoughts about food, particularly among people who struggle with binge eating. The most cited negative effect is nausea in the first weeks, followed by poor sleep, dizziness and headache. Experiences vary widely, and some users notice little difference.
That last point is more honest than the marketing suggests.
In the COR-I trial participants on the highest dose lost an average of 6.1% of body weight after 56 weeks, against 1.3% on placebo. Nearly half passed 5% weight loss, against 16% in the placebo group. Nausea occurred in roughly 30% of participants, against 5% on placebo (Greenway et al., 2010).
How do you titrate Mysimba?
Over four weeks, from one tablet per day to four. The Dutch Farmacotherapeutisch Kompas describes this schedule, and most complaints sit in exactly that build-up period. Taking the steps too fast produces the nausea that makes others stop.
| Week | Morning | Evening | What users often report |
|---|---|---|---|
| Week 1 | 1 tablet | None | Mild nausea, sometimes dry mouth |
| Week 2 | 1 tablet | 1 tablet | Harder to fall asleep, vivid dreams |
| Week 3 | 2 tablets | 1 tablet | Appetite clearly lower, headache possible |
| From week 4 | 2 tablets | 2 tablets | Maintenance dose, complaints usually milder |
The evening dose explains the sleep problem. Bupropion is a substance that increases alertness, and you take it just before the night.
Does Mysimba work better or worse than the injections?
Clearly less powerfully, but it is a tablet. The 6.1% from COR-I sits against 8.4 kilos lost with liraglutide in the SCALE trial (Pi-Sunyer et al., 2015) and up to 20.9% with tirzepatide in SURMOUNT-1 (Jastreboff et al., 2022).
That is not a small difference. It is a factor of three.
For people who do not want injections or cannot tolerate them, Mysimba remains a real option. A full overview of the drugs sits in weight-loss medication, and what the different drugs cost is covered in Mounjaro reimbursement.
Why is blood pressure the point of attention here?
Because bupropion can slightly raise blood pressure and heart rate, while losing weight lowers them. Those two effects work against each other. Mysimba is therefore not suitable with untreated high blood pressure, and that is exactly the group that often wants to lose weight.
That is the most overlooked point about this drug, to my mind.
The Dutch health information service Thuisarts advises contacting your GP about new complaints during medication use. With palpitations, persistent headache or dizziness that applies doubly here.
Which blood values are relevant with Mysimba?
The liver values and the sugar system. Bupropion and naltrexone are both processed by the liver, so ALT is the value you want to know before starting. Alongside it, fasting glucose moves as soon as your intake falls.
Unlike the GLP-1 drugs, the pancreas plays no role here, because the mechanism is entirely different.
Our GLP-1 baseline panel records that starting point, assessed by a BIG-registered doctor. The name refers to the journey, not the drug: the values measured are the same.
Who is Mysimba suitable and unsuitable for?
Your doctor judges that, and the exclusions here are broader than for most drugs. Untreated high blood pressure, epilepsy, a history of eating disorder and opioid use are all reasons not to prescribe it. Naltrexone blocks opioid receptors.
That last point is often forgotten for people taking strong painkillers.
What strikes me about the Dutch experience pages is how rarely those contraindications appear next to the success stories.
If you are considering Mysimba, have your blood pressure and liver values recorded first and discuss the exclusions with your GP.
References
- Greenway FL et al. Effect of naltrexone plus bupropion on weight loss in overweight and obese adults (COR-I). Lancet. 2010. PMID 20673995
- Pi-Sunyer X et al. A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management. N Engl J Med. 2015. PMID 26132939
- Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022. PMID 35658024
- Farmacotherapeutisch Kompas, monograph for naltrexone with bupropion (titration schedule and contraindications).
- Thuisarts, information on complaints during medication use.
Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
Autor
SlimmerLab
Dr. Naimi, lekarz wpisany do holenderskiego rejestru BIG, nadzoruje standardy medyczne naszych treści i ocen. Przeczytaj naszą politykę medyczną
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